1. Field of the Invention
The present invention relates to a chemical analyzer in which chemical analysis films, especially tape-like films (chemical analysis tape), are used to determine the amount of specific components contained in liquid samples, especially biological body fluids such as blood, serum, and urine; and, in particular, to a chemical analyzer which is characterized in the special structure of a tape-feeding cassette for accommodating the tape-like film.
2. Description of the Prior Art
The determination of the amount of various metabolites, e.g. glucose, bilirubin, urea-nitrogen, uric acid, cholesterol, lactate dehydrogenase, creatine kinase, GOT(AST), and GPT(ALT), in body fluids is important in the field of clinical medicine and is essential to the diagnosis of diseases, follow-up studies of medical treatments, judgments on prognosis, etc. In clinical chemical analyses in which blood or the like is used as liquid samples, it is preferable if a highly accurate analysis can be conducted with a very small amount of the liquid sample. Conventionally, wet-type methods which employ reagents solution have been widely used. However, these methods cannot be conducted quickly.
As an analysis means for quickly conducting a highly accurate analysis with a very small amount of a liquid sample, chemical analysis slides in which dry-type multilayer films (film-shaped multi-layer analysis elements) are used have been developed and are disclosed in U.S. Pat. Nos. 3,992,158 and 4,292,272, for example. In a chemical analysis slide, each dry-type multilayer chemical analysis film, in which a support, a reagent layer, a light reflection layer, and a liquid spreading layer are superposed in this order, for example, is accommodated in a mount. One slide is used for one analyte (i.e., one specific component to be analysed) of a liquid sample.
When a long chemical analysis film tape is used instead of such a slide, the time and expense required to provide a slide accommodating a film chip for each unit of analysis can be omitted. Chemical analysis tapes are disclosed, in combination with analyzers, in U.S. Pat. Nos. 3,260,413 and 3,526,480, and the like. Also, U.S. Pat. No. 3,992,158 mentions such a chemical analysis tape. However, as noted in U.S. Pat. No. 3,992,158, in most of those disclosed in U.S. Pat. Nos. 3,260,413 and 3,526,480, at least two tapes are brought into contact with each other so that a complex structure is temporarily formed, and thereafter the tapes are separated from each other. Accordingly, the structure of the analyzer becomes complicated. U.S. Pat. No. 3,992,158 mentions that the analysis tape described therein is advantageous in that it does not require a complicated apparatus and in that various kinds of tapes can be used simultaneously or successively.
In cases where an analysis slide is used for each sample fluid, it is only necessary for the desired number of slides to be taken out of a container or a storage chamber immediately before their use or on the day they are to be used. On the other hand, an analysis tape has to be installed as a whole in an analyzer. Accordingly, when an analysis slide would become unstable during the time it is stored after it has been unpacked and a rolled analysis tape is used instead of a slide, it is necessary that the rolled analysis tape as a whole be accommodated in a cold-storage chamber which keeps the tape at a temperature within the range of 1.degree. C. to 18.degree. C. A chemical analyzer may have such a cold-storage chamber.
In a chemical analyzer which has a cold-storage chamber for accommodating an analysis tape, since the temperature of the tape at the outlet of the cold-storage chamber is low, the atmospheric moisture is likely to form dew on the tape. In this case, the moisture content of the analysis tape increases and the performance thereof will deteriorate. In order for this problem to be overcome, it may be preferable for a low-moisture airflow to be provided near the outlet of the cold-storage chamber. However, even when a low-moisture airflow is provided at the surface of an analysis tape which is taken out of the cold-storage chamber, the deterioration of the analysis tape due to the increase in the moisture content cannot sufficiently be eliminated.
Also, when the tape outlet of the cold-storage chamber is not sealed, the atmosphere may invade the cold chamber and dew may form on the part of the tape near the outlet. It may be desirable for a means for sealing the tape outlet of the cold-storage chamber to be provided at least during the time when the tape is not being conveyed. However, even when a means for sealing the tape outlet of the cold-storage chamber is provided, it is practically impossible to eliminate the deterioration of the analysis tape due to the increase in the moisture content.